This invention relates to a metal-hydrogen alkaline storage cell comprising a rare earth hydrogen absorbing alloy, said cell including a positive electrode and a negative electrode.
In recent years, attention has been paid to a new type of alkaline storage cell which can be substituted for a conventional nickel-cadmium battery, since the former has a higher energy density than the latter. The negative electrode of the alkaline storage cell is made of any hydrogen absorbing alloy belonging to various rare earth groups such as AB.sub.5 group, AB.sub.2 or the like. As the rare earth group forming the foregoing "A" element, an inexpensive misch metal (Mm) is generally used, which is a mixture of lanthanum (La), cerium (Ce), neodymium (Nd), praseodymium (Pr), and the like. The mixture contains Nd in amounts of from about 16 to about 18 weight % and Pr in amounts of from about 5 to about 15 weight %.
When the metal-hydrogen alkaline storage cell uses the misch metal containing the foregoing materials, the problem is that it becomes difficult to absorb and desorb hydrogen in the beginning of a charge/discharge cycle. Since no activation is available in that beginning, the charge/discharge property (in particular, a high efficient discharge property at a lower temperature) is deteriorated.